Human semicircular canal form: Ontogenetic changes and variation of shape and size.

The semicircular canals (SCCs) transduce angular acceleration of the head into neuronal signals, and their morphology has been used to infer function. Once formed, the bony labyrinth, that surrounds the canals, is tightly regulated and has a very low bone turnover. However, relaxed postnatal inhibition of bone remodelling later in ontogeny may allow for some organised adjustments of shape and size or for greater stochastic variation. In the present study, we test the hypotheses that after birth, the shape and size of the bony canal changes or becomes more variable, or both. We study microCT scans of human perinatal and adult temporal bones using a combination of geometric morphometric analysis and cross-sectional measures. Results revealed marginal differences of size (<5%), of cross-sectional shape and of measurement variability. Geometry of the three canals together and their cross-sectional areas were, however, indistinguishable between perinates and adults. These mixed findings are indicative of diminutive levels of relaxed inhibition superimposed over a constrained template of SCC morphology.

Morphological and histomorphometric evaluation of the ventral rectus sheath of the rectus abdominis muscle, fascia lata and pectoral fascia. The beginning of a morphological information bank of human fascias.

The aim of this study was to characterize and compare the morphological and histomorphometric characteristics of the pectoral fascia, fascia lata and ventral rectus sheath. Twenty cadaveric samples of these fascias were analyzed and stained with hematoxylin and eosin, orcein, Van Gieson, Masson's trichrome and Verhoeff¨s stain (1200 slides in total). Morphological evaluation, semiquantitative, morphometric and microdensitometric analysis of elastic fibers present in each of the tissues and a morphometrical analysis of tissue thickness were performed. The mean value of the pectoral fascia thickness was 612±68.13 µm; 84±246 µm for the fascia lata and 584±92 µm for the ventral rectus sheath. The area occupied by the elastic fibers in the pectoral fascia was 12.24±5.84%; 6,54±3.85% for the fascia lata and 11.11±5.26% for the ventral rectus sheath. There were no statistically significant differences when comparing the mean values between the pectoral fascia and the ventral rectus sheath (p=0.07). There were statistically significant differences when comparing the fascia lata to the pectoral fascia and the ventral rectus sheath (p≤0.001). This study reports other morphological characteristics not described in previous histological studies of the analyzed tissues. The results of the morphometric and densitometric analysis in this study reveal that the fascia lata has the fewest elastic fibers of all the tissues analyzed, and the pectoral fascia has the most. These results will be useful for the beginning of a morphological information bank of human fascias.

Characterization and morphological comparison of human dura mater, temporalis fascia, and pericranium for the correct selection of an autograft in duraplasty procedures.

PURPOSE: The objective of this study was to characterize and compare the morphological characteristics of the dura mater, the pericranium, and the temporal fascia to ascertain the most adequate tissue to use as a dura graft. METHODS: 20 dura mater, 20 pericranium and 20 temporalis fascia samples were analyzed. Each of the samples was stained with hematoxylin and eosin, orcein, Van Gieson, Masson's trichrome and Verhoeff-Van Gieson (600 slides in total) for a general morphological evaluation, as well as a quantitative, morphometric and densitometric analysis of elastic fibers present in each of the tissues. RESULTS: The micro-densitometric analysis of the tissues indicated that the area occupied by the elastic fibers showed values of 1.766 ± 1.376, 4.580 ± 3.041, and 8.253 ± 4.467 % for the dura mater, the temporalis fascia and the pericranium, respectively (p < 0.05, all pairs). The values observed in the analysis of the density intensity were 3.42E+06 ± 2.57E+06, 1.41E+07 ± 1.28E+07, and 1.63E+07 ± 9.19E+06 for the dura mater, the temporalis fascia and the pericranium, respectively (p < 0.05), dura mater vs. temporalis fascia and dura mater vs. pericranium). CONCLUSIONS: This is the first study to compare the dura mater with tissues for dural autograft and to quantify the elastic component present in these tissues. The results indicate that the temporalis fascia is a better dural graft because of its intrinsic tissue properties.

Age- and gender-related variations in morphometric characteristics of thoracic spine pedicle: A study of 4,800 pedicles.

Transpedicular spinal fusion is the most commonly used fixation technique for the surgical treatment of vertebral disorders. However, the instrumentation of the thoracic spine using this technique continues to be controversial. The objective of the present study was to determine the morphometric characteristics of the thoracic pedicle and to establish how these characteristics vary with gender and age. Two hundred thoracic spines (4800 thoracic pedicles) from individuals of known gender and age were analyzed (in accordance with the order of vertebrae). The spines were divided into six groups according to age and gender. The horizontal and vertical diameters of the thoracic pedicle were determined for each piece. The mean and standard deviation of each variable were determined, and differences between age groups for each gender were evaluated using parametric correlation tests. The pedicle diameters of men and women differed significantly for most groups (P < 0.05). The horizontal diameters decreased from T1 to T5 and increased up to T12. The vertical diameter followed a cephalocaudal pattern of development from T1-T12. The pedicle diameters decreased with increasing age in women, while the opposite trend was observed in men. In men, the dimensions of the thoracic spine pedicle increase with increasing age; in women, they decrease. These differences should be taken into account when selecting the appropriate pedicle screw.